The prior art has for many years used many and varied methods to form doubled layer materials, especially for the wrapping of rods, tubes, pipes, cables, and other materials to either protect them from their operating environments or to give them strength.
For example the automotive industry has developed safety standards for critical elements in automotive parts such as brake linings to be resistant to failure in high vibration environments and to resist corrosion failures. While these processes, such as in U.S. Pat. No. 5,145,103 issued to Arnold T. Johnson, have used the concepts of electroplating and brazing alloys on the non-ferritic steels surfaces prior to formation of the double wall tubing, thus it was used as a way to spread the brazing. The brazing alloys thus coated the non-ferritic tubing in anticipation of the addition of a selected metal or metal alloy being added to the non-ferric steel tubing surface. Then the method of "fusion" using "Liquidus temperature" was applied to it to cause the selected metal to fuse with the non-ferritic steel by means of the brazing alloys. This fusion process at "Liquidus temperature" was defined as the temperature at which a metal or metal alloy begins to enter its molten state which in this prior art required it to reach the point of brazed fusion between the non-ferritic steel and the metal selected. This temperature of "Liquidus" is a temperature above 1,981 degrees F. in some cases, where the other metal is for example copper. The methods of this type process required also very special and controlled gaseous materials in the various processes to achieve the desired results of theses type methods.
In yet other methods, for example U.S. Pat. No. 2,197,191 issued to Charles A. Nichols etc.,; U.S. Pat. No. 2,234,450 issued to B. L. Quarnstrom; and other methods used by the prior art for bimetallic materials formation, two different materials were simply mechanically wrapped about each other and they were then brazed at their points of union to form a bimetallic tube. In some cases these finished bimetallic tube materials were then electroplated with tin, zinc, cadmium etc., after these tubes had been cut into the desired lengths and shapes. While these methods formed usable bimetallic materials for some applications they were not very successful in environments where corrosive liquids worked their way through the outer jacket through small or microscopic holes because there were no bonds between the two wrapped materials and thus the corrosive fluids seeped and flowed therebetween and could corrode the whole interior material and cause failure therein. The one advantage of this type prior art was the ability to get a bimetallic material which had a relatively thick outer layer of material and because of the mechanical nature of the wrapping they formed a more ductile material also.
In yet other prior art such as methods using conventional hot dip galvanized coating by hot dipping of one material, such as an iron formed material, into another at a liquid state, such as Zinc at 450 degrees C., the ability to get relatively thick outer or second layers of the liquified material on the dipped material was limited to thickness of about 80 microns of thickness and therefor limited the usefulness of the resulting products of this process. Further there were formed in such processes intermetallic compounds of Fe-Zn in the case of the use of those materials, which caused brittleness in the bimetallics using the methods of the hot dip type. Further in these type process very high temperatures and controlled conditions were required as these operations occur at liquid or molten metal states with the problems inherent with those processes.
In some prior art the use of mechanical cladding was accomplished by placing a brazing material on one sheet or the other or both and then rolling them together under pressure rollers and applying heat sufficient to cause the materials to stick together. While this provided a bimetallic material, it produced one which had very limited integrated ductility and almost no bonding of the two materials together, other than as a glue would bind two piece of material together.